CORE C: HUMAN CONSULTATION, BIOSAMPLES, BIOMARKERS (CBB) ABSTRACT The Human Consultation, Biosamples, Biomarkers (CBB) Core (Core C) will complement and integrate the Projects of the P01 Strategies for Targeting Reactive Astrocytes in AD and ADRD. It is critical to validate the translational relevance of mechanistic mouse models, and to extend those results toward further clinical studies. Yet there are challenges when it comes to addressing the complex pathobiology of the dementia clinical syndrome. Core C will bridge those critical gaps through the following Specific Aims: Aim 1: Optimize clinically-relevant study design and manage ongoing data streams incorporating human biomarker and autopsy data. This Aim will foster integration, organization, coherence, and documentation for Core C. The multimodal data include molecular, metabolic, and network-wide domains in human endophenotypes, and human preclinical and clinical endpoints. Aim 2: From existing autopsy material and data, generate a set of human cases from the UK-ADRC that encompasses the AD/ADRD phenotypes studied in all 4 Projects (AD, VCID, LATE+HS, and controls) and provides a common basis for downstream biochemical and neuropathological endpoint assessments relevant to the Projects. We will analyze a panel of 100 cases for this Aim. Aim 2a: Biochemistry. We will perform multi-level protein extracts and run immunoblots with quantitative measurements on each sample with astrocytic proteins (e.g., AQP4, Kir4.1, GFAP, SLC1A2, ABCC9/SUR2, Insulin receptor) being studied in the Projects. We will separately assess snap-frozen hippocampal samples, as well as frontal cortex (Brodmann Area 9) white matter and gray matter seperately. Aim 2b: Neuropathology. Neuropathologic endpoints will be characterized in a quantitative manner in the same panel of 100 cases: Astrocytosis (GFAP+), Aβ plaques, TDP-43 proteinopathy, and Tau tangles. We also will perform highly quantitative assessments of blood vessel morphology using CD34 (capillaries) and ?- SMA (arteriole) markers. Double-label IFC will characterize IR and SUR2 proteins’ cellular distributions. Samples will also be genotyped for ABCC9 risk alleles. Aim 3: From existing clinical outcome measures, generate a set of biomarker (in vivo) data from human participants that represents a common basis for downstream biofluids and neuroimaging endpoint assessments relevant to the projects. Aim 3A: Neuroimaging. A 3D anatomical magnetization-prepared rapid acquisition with gradient echo (MPRAGE), cerebrovascular reactivity (CVR), from existing human imaging on a 3T MRI scanner will be generated and provided to Projects and Core D. Drs. Powell and Bahrani in Core C are also performing parallel neuroimaging experiments in mice (Core B). Aim 3B: Fluid Biomarkers. Cerebrospinal fluid (CSF) and plasma that are banked from UK-ADRC and UK-MarkVCID participants will be assayed for MMP9 and GFAP using Quanterix Simoa assays and AQP4, Kir4.1 and Dp71 will be assayed...